|GeoCam has to be considered a great success.
Unfortunately, not a single target was obtained that matched a Skylab EREP target area.
This was a result of several factors including a 28.5o orbital inclination as
opposed to Skylabs 50o inclination, and a change in launch dates which
put the Western Hemisphere (where most EREP targets are located) in darkness. More to the
point, it clearly demonstrated that the space shuttle is not a suitable platform for
highly specific targeting. The short mission duration does not allow for the required
confluence of exact orbital track, sun angle, shuttle orientation, and clear weather. The
International Space Station, on the other hand, is a perfect platform with an orbital
inclination nearly identical to Skylab and the long timeline necessary to systematically
duplicate the EREP images. The concept is as valid today as it was in 1992, but now there
is a real opportunity to produce images of great educational and scientific value. The
EREP images are now over a quarter of a century old, and differences will be all the more
observable, and important. They can serve as a means to better understand and measure
environmental degradation. The long baseline will more clearly separate long term changes
from transient or short-term cyclical events. Historical examinations of change often look
far back into Earth's history to determine the rate and degree of natural changes. The
rapid growth of human population presents fundamentally different pressures on the Earth's
ecosystem. To gain new insight on human-induced changes, earth scientists focus on the
changes that have occurred over a shorter time span (25 years). During this time, natural
and human induced changes on the surface of the earth have been photographed from space.
Comparison between photos past and present enables documentation of profound changes to
the Earth. One of the largest early data sets of earth observing photographs comes from
the Skylab archives. These photographs covered much of the Earth's surface, and are an
important baseline with which to compare present and future photographs. It is the major
goal of the GeoCam II project to provide a direct link to this resource.